Single step sterilization wrap system

ABSTRACT

Disclosed herein is a single step sterilization wrapping material suitable for use, as an example, in wrapping surgical instruments and supplies for sterilization, transportation and storage. The material includes separate inner and outer wraps which, unlike previous wraps, are joined to one another. Common wrapping techniques involve wrapping items to be sterilized with two separate sheets of wrap. The present invention provides separate wraps which can be specially engineered to deliver specific properties for each sheet and then joined to one another so as to permit wrapping and opening in a neat single step process which increases efficiency and saves time and money. In special situations the outer wrap can be engineered with increased strength, the inner wrap with increased barrier properties and the inner and outer wraps can be made visually distinct from one another so that improper wrapping or opening, is not a problem.

This is a divisional of application Ser. No. 09/045,769, filed Mar. 20,1998, now U.S. Pat. No. 5,958,337, which is a continuation ofapplication Ser. No. 08/789,741, filed Jan. 27, 1997, now abandoned,which is a continuation of application Ser. No. 08/468,164, filed Jun.6, 1995, now U.S. Pat. No. 5,635,134, which is a divisional ofapplication Ser. No. 08/381,060, filed Jan. 31, 1995, now abandoned,which is a continuation of application Ser. No. 08/084,851, filed Jun.30, 1993, now abandoned.

BACKGROUND OF THE INVENTION

The present invention is directed to sterilization wrap materials. Moreparticularly, the present invention is directed to multi-plied materialsmade from individual sheets which are fused together so as to besuitable for use as a sterilization wrap for wrapping surgicalinstruments and supplies for sterilization and storage in conjunctionwith surgical procedures and for other applications such as packagingitems for bone marrow units.

Personnel in the Central Service Room (CSR) or the Sterile ProcessingDepartment (SPD) of hospitals are commonly charged with theresponsibility of packaging surgical supplies to ensure that thesterility of the packaged contents are maintained all the way fromsterilization to the point of reuse. Several activities are involved inthe task of sterile supply delivery to the operating room and otherunits.

Much of the surgical instruments and supplies used in the operating roomare reusable. These supplies typically include such things as clamps,scalpel blade handles, retractors, forceps, scissors, surgeons towels,basins and the like. All of these supplies must be collected after eachprocedure and sterilized before they can be used again in anotherprocedure. To this end, the supplies are placed in stainless steelinstrument trays, and soft goods such as surgeons towels, drapes, andgowns are prepared for packaging. Then, the trays and package contentsare each generally wrapped with two sheets of material commonly referredto as sterilization wrap.

The sterilization wrap is usually a woven or nonwoven material whichwhen wrapped around the tray or package contents in a certain prescribedmanner will permit the entry of sterilizing vapor/gas or other medium tosterilize the contents of the tray while denying the ingress ofcontaminants such as bacteria and other infectious causing materials ortheir vehicles after sterilization. Generally, the two primary means forsterilizing instruments are autoclaving with steam and ethylene oxidesterilization.

Using a wrapped tray as an example, once the wrapped tray and itscontents have been sterilized, the wrapped tray is transported to thepoint of use, typically an operating room, or is stored until it isready to be used. During storage and transfer to the operating room, thewrapped tray may be handled several different times. Each time thewrapped package is handled, there is a potential that the sterile natureof the package contents can be compromised. The two most common ways thewrapped package can be compromised are a tear or other breach of thewrapping material, and wetness or foreign materials identified on theouter wrapper, which would warrant a premature unwrapping.

In order to promote and maintain the sterility of the packaged contents,the Association of Operating Room Nurses (AORN) has developed certainrecommended practices for the wrapping and handling of in-hospitalprocessed packages. It is common practice among many hospitals asrecommended by the AORN to "double wrap" in-hospital processed packages.A primary method of double wrapping is "sequential" in nature in thatthe package contents are first wrapped by one sheet of sterilizationwrap and then wrapped again by another sheet of sterilization wrap.Another method of double wrapping is "simultaneous" in nature in thatthe package contents are wrapped by two sheets of sterilization wrap atthe same time. That is, two sheets of sterilization wrap are aligned oneon top of the other, and the item to be wrapped is placed on top of thetwo sheets, then the item is wrapped by both sheets of material at thesame time.

Studies have been used to track packages from initial wrapping, all theway through sterilization, storage, handling, transfer, unwrapping andultimate reuse. These studies indicate that the frequency ofcompromising wrapped items due to tears or holes has been reducedbecause of improved handling and storage techniques and because ofimproved sterilization packaging products. One of the main thrustsbehind such efforts has been economics. Every time a sterile package iscompromised, it must be taken out of circulation, unwrapped, rewrapped,and resterilized before it can properly be reused. This wastes time andmoney.

While the frequency of compromising wrappers has been reduced thusresulting in the saving of time and money, the use of simultaneouswrapping techniques would further increase the time savings in wrappingand opening packages and thus result in a still greater cost savings.Simultaneous wrapping takes less time than sequential wrapping andrecent research in hospitals has shown simultaneous wrapping to be justas effective as sequential wrapping in maintaining sterility absent abreach in the wrap which is generally independent of the manner ofwrapping.

Even though the hospital staff may desire to simultaneously wrap insteadof sequentially wrap, the time it takes to set up the outer and innersheet wrappers and the awkwardness of manipulating loose wrappers duringsimultaneous wrapping can offset the time savings hoped to be achievedwhen attempting to move away from sequential wrapping. Consequently, ifa product existed which provided the appropriate inner and outer sheetcombinations and eliminated the awkwardness of keeping the two sheetstogether during the package wrapping and opening processes, then asimultaneous packaging system would deliver the benefits desiredincluding time savings and targeted engineered inner and outer sheetperformance.

In conjunction with the manner in which the packages are wrapped, thematerial used for wrapping is also important. As mentioned above, thetwo most common wrapping materials are woven materials such as cloth(cotton/polyester), nonwoven materials such as KIMGUARDO® Sterile-Wrap(polypropylene) from Kimberly-Clark Corporation of Neenah Wisconsin andBio-shield CSR Wrap (wood pulp/polyester) from Baxter HealthcareCorporation of Deerfield, Illinois. One version of the Baxtersterilization wrap is a product called DualWrap® Sterilization Wrap,which includes an inner sheet of wet laid paper (cellulose) and aseparate outer sheet of spunlaced or hydroentangled pulp/polyester. Theinner and outer layers are provided in a stack of loose, unattachedsheets in which the inner and outer sheets are alternated.

Whatever the material is that is being used as sterile wrap, it shouldbe noted that when wrapping two sheets at the same time, it is importantthat the wrapping materials provide good barrier properties to maintainpackage sterility and good strength properties so that tearing or otherforms of breaching are held to a minimum. If the outer and inner sheetsof the double wrap are to have different properties, then it isimportant that the system be visually identifiable so that the user candetermine which wrapper is the outer sheet and which wrapper is theinner sheet. Consequently, there is a need for a new sterilization wrapsystem that actually reduces the time for packaging and opening anddelivers outer and inner sheet engineered performance in a simpleidentifiable and easy to use fashion. Such attributes are provided bythe present invention as will become more apparent upon a further reviewof the following specification, claims and drawings.

SUMMARY OF THE INVENTION

Disclosed herein is a single step sterilization wrap system for wrappingitems in packages which are to be sterilized and maintained in asterilized condition until use such as surgical instruments for hospitaloperating room use. A large number of such items are currently wrappedby two separate sheets of sterilization wrap. The most common method ofwrapping such items is called double, sequential wrapping wherein anitem is wrapped in a first piece of sterilization wrap with the looseends being taped shut. Next, a second and separate sheet ofsterilization wrap is used to wrap the item a second time. Once thesecond sheet of wrap has been wrapped around the item, the loose ends ofthe second sheet are taped closed and the wrapped item is sent through asterilization process. After the wrapped item has been sterilized, it isnormally placed in storage until actual use at which time the wrappedand sterilized package is removed from storage and transported to theoperating room where the sterile wrap is removed and the items aresubsequently used. A second and less commonly used method of wrapping iscalled the simultaneous wrapping wherein two sheets of sterilizationwrap are placed one on top of the other, aligned and then the two sheetsare wrapped about the item to be sterilized at the same time. Afterwrapping is complete, the loose ends are taped shut and the item is sentthrough the same sterilization process as described above.

The present invention provides an improved means for simultaneouslywrapping and unwrapping items which must be sterilized prior to use.This is accomplished by bonding or joining two separate sheets ofsterilization wrap together at one or more locations to create a singlestep system wherein the separate sheets are prealigned and joined to oneanother to facilitate the wrapping process as well as the unwrappingprocess. As a result, the amount of time needed to wrap and unwrap anitem is decreased and the ease of wrapping is improved. In addition,each of the individual sheets of the single step sterilization wrapsystem can be specifically engineered or designed to impart special ordifferent features to the overall system.

The single step sterilization wrap system includes an outer wrap madefrom a first sterilization sheet which is superposed on an inner wrapmade from a second sterilization sheet with each of the sheets beingindependent of one another and joined to one another at one or more bondsites. The individual inner and outer wraps can be made from a varietyof sterilization materials including fibrous materials such as nonwovensand wovens. The sterilization wrap system has a first exterior surfaceand a second exterior surface formed by the opposed sides of the systemwith each of the surfaces having respective surface area and wherein thebond sites joining the inner and outer wraps together occupy no morethan 50% of the surface area of either the first or second exteriorsurfaces of the sterilization wrap system. The inner and outer wraps canbe joined to one another in a variety of bonding patterns including bothlong continuous seams and point bonding. If desired, the sterilizationwrap system can define a first zone and a second zone with the firstzone having a greater number of the bond sites than the second zone andwherein the second zone is surrounded by the first zone so that thesterilization wrap system has an area of low density bonding surroundedby an area of higher density bonding.

Each of the individual sheets can be designed to have particularproperties which may be the same or different from the other sheet ofthe single step sterilization wrap system of the present invention. Forexample, the outer wrap can be made stronger than the inner wrap asindicated by the outer wrap having a greater grab tensile strength ascompared to the inner wrap. In addition, the barrier properties of theinner wrap can be fortified to create a better means of filteringbacteria than the outer wrap.

The inner wrap and outer wrap can both be made from nonwoven laminatessuch as spunded/meltblown/spunded laminates wherein the inner meltblownlayer provides barrier properties and the outer spunbonded layersprovides strength. By using a heavier basis weight meltblown layer inthe inner wrap as compared to the outer wrap, the inner wrap will have abetter barrier property than the outer wrap in which case the inner wrapwill have a lower dry spore penetration rate than the outer wrap and agreater bacterial filtration efficiency than the outer wrap. Conversely,the meltblown layer of the inner wrap can be decreased to such an extentthat the bacterial filtration efficiency of the inner wrap is less thanthe outer wrap. Furthermore, the strength of the inner and outer wrapscan be varied by varying the basis weight and the types of polymersbeing used to form the fibers which make up the individual layers of therespective laminates. As a result, a sterilization wrap system can bedesigned wherein the peak energy of the outer wrap is greater than theinner wrap.

In situations where the inner wrap has different design properties thanthe outer wrap, it is important that the end user be able to determinewhich of the two-wraps (inner or outer) should be placed adjacent theitem being wrapped and subsequently sterilized. To this end, the innerand outer wraps can be designed so as to be visually distinct fromanother as by printing or other indicia as well as the use of differentcolors or shades with respect to the individual sheets of sterilizationwrap.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a single step sterilization wrapaccording to the present invention with a sterilization tray ready forwrapping placed on top of the sterilization wrap.

FIG. 2 is a cross-sectional side view of a single step sterilizationwrap according to the present invention.

FIGS. 3 through 6 are top plane views of additional single stepsterilization wraps according to the present invention with differentbonding patterns for joining the separate sterilization wrap sheetstogether.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein is a sterilization system suitable for use withsimultaneous wrapping procedures for wrapping, sterilizing, storing andusing sterilized items such as surgical supplies. While the presentinvention will be described in conjunction with its use in hospital andsurgical room procedures, the sterilization system of the present systemis intended for use wherever there is a need for sterilized materials.consequently, the following description of the present invention shouldnot be considered a limitation as to the scope of use of the presentinvention.

Referring to FIGS. 1 and 2 of the drawings, there is shown asterilization system or wrap for containing and maintaining sterility ofsurgical supplies and the like. The sterilization system 10 includes anouter wrap 12 also referred to as a strength reinforced barrier weblaminate and an inner wrap 14 also referred to as a barrier weblaminate. As can be seen from FIG. 1, the outer wrap 12 and inner wrap14 are placed in face to face relationship with one another, one on topof the other in vertical juxtaposition. Each of the wraps are of thesame general size and shape. Most typically the wraps will be square orrectangular in shape. As a result, each wrap will have at least twogenerally parallel edges a,a' and b,b' located along their peripheries16.

To facilitate wrapping of an item 18 such as is shown in FIG. 1, theouter wrap 12 and the inner wrap 14 are attached to one another in amanner so as to hold the two wraps 20 together while still maintainingtheir visual distinctiveness so that the end user can visually see thatthe item is being wrapped by two separate sheets of sterile wrap.Generally the two wraps will be joined about all or a portion of theirperipheries 16. As specifically shown in FIGS. 1 and 2, the two wrapsare joined to one another along the entire length of two generallyparallel edges of the wrap, a-a' and b-b'. The edges can be joined toone another by any number of suitable means including, but not limitedto, adhesives, stitching, heat bonding and ultrasonic bondingcollectively referred to as joining. As shown in FIGS. 1 and 2, the bondsites 20 are perfected by ultrasonic bonding, are continuous, and runthe entire length of the edges just interior to or along the periphery16 on opposed sides of the sheets 12 and 14.

In addition to or as an alternate to the continuous bonds or seams 20, asecond set of bonds 22 may be used to secure the two wraps together. Thebonds 22 in FIG. 1 are a series of spaced-apart and separate bond pointsin the form of two rows of parallel but spaced apart rectangles or othershapes with the rectangles in one row being offset from the other row sothat they are in overlapping relationship if the system lo were viewededge on. This bond pattern has been used to seam sleeves on disposablesurgical gowns manufactured by the assignee of record, Kimberly-ClarkCorporation of Neenah, Wis. The bonds 22 can be just interior of thecontinuous bonds 20 and serve to further join the two wraps 12 and 14together when used alone or in conjunction with the continuous bonds 20.

It also is possible to effect bonding between the two wraps 12 and 14 ina variety of other manners which are exemplified, at least in part, inFIGS. 3 through 6. In FIGS. 3 through 6, the inner and outer wraps aresuperposed and joined to one another by one or more bond sites which maybe long continuous bond lines such as are shown in FIGS. 3 through 5 ora plurality of localized bond points such as are shown in FIG. 6. InFIG. 3, which is. a top plane view, the outer wrap 12 and inner wrap 14of the system 10 are bonded together by two crisscrossing bond lines 28and 30 which form a "X" pattern across the surface of the system 10. InFIG. 4, the outer wrap 12 and the inner wrap 14 of the system 10 arebonded to one another by a series of parallel bonds 32 which span all ora portion of the length or width of the system 10. In FIG. 5, a seriesof sinusoidal bonds 34 are provided.

In addition to or in conjunction with the relatively long bonds or seamsshown in FIGS. 3 through 5, the outer wrap 12 and the inner wrap 14 ofthe system 10 may be joined by a plurality of localized, discontinuousbond points 36 such as are shown in FIG. 6. These bond points may beuniformly spaced across the surface of the system 10 or they may bebroken into two or more zones with each of these zones having varyingdegrees or densities of bond sites. Referring specifically to FIG. 6,the system 10 is divided into a first zone 38 and a second zone 40which, for purposes of illustration, are shown in FIG. 6 as beingseparated by an imaginary dashed line 42. The first zone 38 has agreater number of the overall plurality of bond sites per unit area thanthe second area 40. In addition, the first zone 38 completely surroundsthe second zone 40 thereby creating a system 10 wherein the periphery ofthe system 10 has a generally greater degree of bonding than the centralportion of the system 10.

Other combinations of bonding patterns can also be used. For example,indicia, logos and other printed matter can be used as the bond patternto bond the outer wrap 12 to the inner wrap 14. Thus the bond patterncould be wording such as "KIMBERLY-CLARK" or "KIMGUARD®".

An important feature of the present invention is that the user of thesingle step sterilization wrap system of the present invention canvisually perceive that the system does in fact include two separatesheets of sterilization wrap. Being able to see this reinforces thecomfort level of the user that the wrapped item is protected by not onebut two sheets of sterilization wrap. Thus the two sheets ofsterilization wrap should be joined to one another with a sufficientamount of bonding so that the two sheets do not separate, but not withso much bonding that the two sheets appear to be one. To this end, thesterilization wrap system 10 can be viewed as having a first exteriorsurface 44 and a second exterior surface 46 on opposed sides of thesystem 10. See FIG. 2. To maintain the visual distinctiveness of the tworespective surface areas it is advantageous if the surface area of thebond sites do not occupy more than about 50 percent of the surface areaof either the first or second exterior surfaces 44 and 46 of thesterilization wrap system 10.

While wishing to maintain the visual distinctiveness of the outer wrap12 and inner wrap 14, the two sheets of wrap should be sufficientlyjoined to one another so that they do not readily separate from oneanother throughout the process of removing the sterilization wrap fromits original packaging, wrapping the items to be sterilized with thewrap and unwrapping the sterilized items for use. Consequently, it isdesirable that there be at least a one pound tensile force needed toseparate the joined sheets from one another.

Generally, the bonded wraps come in several sizes to wrap various sizeitems and trays. Typical sizes include 18, 24, 30, 36, 40, 45, 48 and 54inch square wrappers as well as 54×72 inch rectangular wrappers. To wrapan item, in this case a sterilization wrap tray 18 such as shown in FIG.1, the item is placed on top of the system 10 in contact with the innerwrap 14 such that the four corners of the wrap can be folded over ontothe package one at a time. Once the folding is completed, the wrap issealed with tape and the wrapped package is ready to be sterilized.

Each of the wraps can have its own special characteristics. The mainfunction of the inner wrap 14 is to act as the primary filtrationbarrier while the primary function of the outer wrap 12 is to providestrength with a secondary function of also providing a barrier tobacteria and other contaminants.

Both the outer wrap 12 and the inner wrap 14 can be made from a numberof materials. Sterilization wraps are generally characterized as fallinginto two main classes, reusables and disposables. Reusables arematerials which, as the name suggests, can be reused, typically bywashing or some other form of cleaning. Disposables, on the other hand,are usually one-use items which are discarded or recycled after theirinitial use. Generally, cloth, linen or other woven materials fall intothe reusable category while disposables normally include nonwovenmaterials made from either or both natural and synthetic fibers such aspaper, fibrous polymeric nonwovens as well as films which are capable ofpassing sterilants and retarding transmission of bacteria and othercontaminants.

Nonwoven sterilization wraps have become particularly well-liked due totheir barrier properties, economics and consistent quality. The nonwovenmaterials can be made from a variety of processes including, but notlimited to, air laying processes, wet laid processes, hydroentanglingprocesses, spunbonding, meltblowing, staple fiber carding and bonding,and solution spinning. The fibers themselves can be made from a varietyof both natural and synthetic materials including, but not limited to,cellulose, rayon, polyesters, polyolefins and many other thermoplasticmaterials. The fibers may be relatively short, staple length fibers,typically less than 3 inches, or longer more continuous fibers such asare produced by spunbonding and meltblowing processes. Whatevermaterials are chosen, the resultant wrap must be compatible with theparticular sterilization technique being used and must also provide bothstrength and barrier properties to maintain the sterile nature of thewrapped contents until use.

It has been found that polyolefin-based fibers and their resultantnonwovens are particularly well-suited for the production ofsterilization wrap. Polypropylene spunbonded nonwovens such as areproduced by the Assignee of record, Kimberly-Clark Corporation, can beused to impart strength characteristics to the sterilization wrap and inparticular, the outer wrap 12. In more refined embodiments, the outerwrap 12 can be made from laminates such as a laminate of spunbonded andmeltblown or spunbonded, meltblown, spunbonded to impart both strengthand barrier properties to the outer wrap 12.

A spunbonded, meltblown, spunbonded material is made from three separatelayers which are laminated to one another. The method of making theselayers is known and described in commonly assigned U.S. Pat. No.4,041,203 to Brock et al which is incorporated herein in its entirety byreference. The material of Brock et al is a three layer laminate ofspunbonded/meltblown/spunbonded layers which is also commonly referredto by the acronym "SMS". The two outer layers of SMS are a spunbondedmaterial made from extruded polyolefin fibers laid down in a randompattern and then bonded to one another. The inner layer is a meltblownlayer also made from extruded polyolefin fibers generally of a smallerdiameter and sometimes having a more discontinuous length than thefibers in the spunbonded layers. As a result, the meltblown layerprovides increased barrier properties due to it fine fiber structurewhich permits the sterilizing agent to pass through the fabric whilepreventing passage of bacteria and other contaminants. Conversely, thetwo outer spunbonded layers provide a greater portion of the strengthfactor in the overall laminate.

A particular feature of the present invention is the specific tailoringavailable for each of the layers in the respective outer wrap 12 andinner wrap 14. While the two wraps can be identical to one another, inmore refined embodiments of the present invention the outer wrap 12 isdesigned to have higher strength properties than the inner wrap 14. Thisis to provide a stronger barrier to tears and other possible breaches ofthe wrapped item from exterior objects. Conversely, in more refinedembodiments of the present invention, the inner wrap 14 is designed tohave higher barrier properties than the outer wrap 12. Adjusting thebarrier and strength properties can generally be accomplished byadjusting the basis weights of the outer and inner wraps as well as thebasis weights of each of the individual layers within each of the wraps.Suitable basis weight ranges for either of the wraps range between about0.5 and about 3.5 ounces per square yard (osy).

One particular example of a single step sterilization wrap systemcomprises an outer wrap made from a strength barrier web laminate and aninner wrap made from a barrier web laminate with the strength barrierweb laminate and the barrier web laminate being placed adjacent to oneanother in generally face-to-face or superimposed relationship with thelaminates being joined to one another at one or more bond sites. Each ofthe layers are made from a spunbonded/meltblown/spunbonded laminate astaught, for example, by U.S. Pat. No. 4,041,203. Thus the strengthbarrier web laminate can comprise a first strength layer made fromrandomly deposited fibers, a second strength layer made from randomlydeposited fibers and an intermediate barrier layer made from randomlydeposited fibers with the fibers in the intermediate barrier layerhaving an average fiber diameter which is less than the average fiberdiameter of the fibers in either of the first or second strength layers.In addition, the intermediate barrier layer is disposed between andbonded to the first and second reinforcing layers. This strength barrierweb laminate will generally form the outer wrap 12. The inner wrap 14can be made from a barrier web laminate comprising a third strengthlayer made from randomly deposited fibers and a fourth strength layermade from randomly deposited fibers with a second intermediate barrierlayer made from randomly deposited fibers. Here again the fibers of thesecond intermediate barrier layer have an average fiber diameter whichis less than the average fiber diameter of either the third or fourthstrength layers and the second intermediate barrier layer is disposedbetween and bonded to the third and fourth strength layers. To provideadded strength, the outer wrap comprised of the strength barrier weblaminate can have a greater grab tensile strength than the inner wrapand the inner wrap made from the barrier web laminate can have a dryspore penetration rate which is lower than the outer wrap and abacterial filtration efficiency which is greater than the outer wrap.

When designing inner and outer wraps with different properties it isusually important that system 10 be positioned such that proper wrapsurface faces the item to be wrapped and the other wrap surface facesaway from the wrapped item. Typically this will mean that the inner wrap14 is in contact with the item 18 to be wrapped and the outer wrap 12will be positioned away from the wrapped item 18. To this end it may bedesirable to produce inner and outer wraps which are visuallydistinguishable from one another. By "visually distinguishable" it ismeant that a majority of people who routinely use such materials wouldbe able to tell the difference between the first exterior surface 44 andthe second exterior surface 46 of the system 10 based upon a visualobservation of the two surfaces. One means of achieving this would beshading or coloring the inner wrap 14 differently than the outer wrap12. In addition, printing or other indicia could be used todifferentiate the two wraps from one another.

To demonstrate the attributes of the present invention, severalsterilization wrap systems 10 were prepared and then tested againstother currently available sterilization wraps. Several of these wrapsincluding samples of the present invention were wrapped aroundsterilization packages and then sent through a representativein-hospital handling process after which, the contamination rate of thetrays was measured. In addition, the attributes of certain components ofthe present invention were compared to the components of other availableproducts.

Kimberly-Clark Corporation, the assignee of record, manufactures aseries of single sheet sterilization wrap materials made fromspunbonded/meltblown/spunbonded laminates. These materials are availablein a variety of basis weights as indicated below in Table I.

                  TABLE I                                                         ______________________________________                                                              Basis Weight - total (per layer)                        Wrap Type  Grade      (s/m/s)                                                 ______________________________________                                        SPUNGUARD ® 1                                                                        Light      1.05 osy (.35/.35/.35)                                  Sterilization Wrap                                                            SPUNGUARD ®                                                                          Regular    1.2 osy (.375/.45/.375)                                 Sterilization Wrap                                                            SPUNGUARD ®                                                                          Heavy      1.5 osy (.525/.45/.525)                                 Sterilization                                                                            Duty                                                               Wrap                                                                          SPUNGUARD ®                                                                          Super      1.85 osy (.7/.45/.7)                                    Sterilization                                                                            Duty                                                               Wrap                                                                          KIMGUARD ®                                                                           Regular    1.4 osy (.45/.5/.45)                                    Sterile Wrap                                                                  KIMGUARD ®                                                                           Midweight  1.8 osy (.65/.5/.65)                                    Sterile Wrap                                                                  KIMGUARD ®                                                                           Heavy Duty 2.2 osy (.85/.5/.85)                                    Sterile Wrap                                                                  KIMGUARD ®                                                                           Ultra      2.6 osy (1.05/.5/1.05)                                  Sterile Wrap                                                                  ______________________________________                                    

Two sterilization wrap systems 10 were prepared according to the presentinvention. One of the two systems had a lower overall basis weight andtherefore is referred to as a regular grade. The second sterilizationwrap system had a higher overall basis weight, and therefore, wasreferred to as a heavy grade. The outer wrap 12 of the regular gradesystem 10 was a spunbonded/meltblown/spunbonded laminate with an averageoverall basis weight of 1.4 ounces per square yard. The two outer layersof the outer wrap 12 each had a basis weight of 0.55 ounces per squareyard and the inner layer of meltblown had a basis weight of 0.3 ouncesper square yard. The inner wrap 14 of the regular grade system 10 had anaverage overall basis weight of 1.4 ounces per square yard includingindividual outer spunbonded layer basis weights of 0.45 ounces persquare yard and an inner meltblown basis weight of 0.5 ounces per squareyard. The outer wrap 12 and the inner wrap 14 were ultrasonically bondedtogether in the same fashion as the bonding shown in FIG. 1 includingtwo continuous bonds along two opposed parallel edges of the system anda series of spaced-apart bonds just interior to each of the continuousseam bonds. The opposite opposed edges were not bonded. The heavy gradesterilization wrap system 10 had an outer wrap 12 made from aspunbonded/meltblown/spunbonded laminate with an average overall basisweight of 2.6 ounces per square yard. The outer wrap 12 was made fromtwo layers of spunbonded fibers each of which had a basis weight of 1.05ounces per square yard and a middle meltblown layer having a basisweight of 0.5 ounces per square yard. The inner wrap 14 of the heavyduty grade sterilization wrap system 10 was also made from aspunbonded/meltblown/spunbonded laminate and had an average overallbasis weight of 1.8 ounces per square yard. This wrap 14 included twoouter spunbonded layers each of which had a basis weight of 0.65 ouncesper square yard and an inner layer of meltblown having a basis weight of0.5 ounces per square yard. The outer wrap 12 and inner wrap 14 werebonded to each other in the same fashion as the regular gradesterilization wrap system described above. These two systems accordingto the present invention were tested against two sheets of unattachedsterilization wrap produced by Baxter Healthcare of Deerfield, Ill. andsold as DualWrap® sterilization wrap. The DualWrap® sterilization wrapis sold to customers in a box in loose sheet form with a hydroentangledouter sheet and a paper-based inner sheet alternated in the box and withthe individual sheets being unattached to one another. The DualWrap®sterilization wrap had an overall basis weight including both sheets of3.57 ounces per square yard. This wrap included a heavier outer sheetwith a basis weight of 2.02 ounces per square yard and a lighter innersheet with a basis weight of 1.55 ounces per square yard.

Each of the individual sheets of the samples were tested in the machineand cross-directions for grab tensile strength in pounds and peak energyin inch-pounds. The samples were also tested for dry spore penetrationin parts per thousand and bacterial filtration efficiency as apercentage. Each of the samples were also tested for Frazier porosity incubic feet per square foot per minute. The grab tensile strength andpeak energy measurements were performed in accordance with Federal TestMethod Standard 191A, Method 5100 as modified by 1992 protocol. The dryspore talc filtration efficiency test measures the ability of a fabricto resist the penetration of bacteria on dry talc particles. A stream ofair, moving at one cubic foot per minute and carrying talc particleswith a range of average diameters of 1 to 9 microns, was pumped throughthe sterilization wrap to agar-filled petri dishes below. Attached tothe particles was Bacillus Subtilis, var. Globgii. The dishes werecultured at 37° C. (plus or minus 2° C.) for 24 hours. Bacterialcolonies were then counted to determine the filtration efficiency andthe efficiencies were then reported as the number of particles per onethousand penetrating particles. This testing was performed on theindividual sheets pursuant to standard operating procedure ARO-003.

The bacterial filtration efficiency test is a measurement of the abilityof a material to prevent the passage of bacteria completely throughitself. To determine this, a culture of Staphylococcus aureus wasdiluted in 1.5% peptone water to a precise concentration. The culturesuspension was pumped through a `Chicago` nebulizer at a controlledflowrate and fixed air pressure. The constant challenge delivery at afixed air pressure formed aerosol droplets with a mean particle size(MPS) of approximately 3.0 um. The aerosol droplets were generated in aglass aerosol chamber and drawn through a six-stage, viable particle,Andersen sampler which contained single sheets of the various wrapsbeing tested. The collection flowrate through the test sample andAnderson sampler was maintained at 28.3 LPM (1 CFM). Test controls andtest samples were challenged for a 2 minute interval. A total of fivesamples were run for each of the materials tested.

The delivery rate of the challenge also produced a consistent level of2200±500 colony forming units (CFU) on the test control plates. A testcontrol was run using no filter medium in the airstream. The requirementfor the test control was that the control average fell within the rangeof 1700-2700 colony formed units (cfu). Test controls were run 4 to 5times a day. A reference material was also included after every set oftest samples. The standard reference material used had filtrationefficiencies of 97.5%±1.0.

The Anderson sampler, a sieve sampler, impinged the aerosol dropletsonto the six agar plates based on the size of each droplet. The agarmedium used was soybean casein digest agar (SCDA). The agar plates wereincubated at 37° C.±2° C. for 48 hours and the colonies formed by eachbacteria laden aerosol droplet counted and converted to `probable hit`values using the hole conversion chart provided by Andersen. Theseconverted counts were used to determine the challenge level delivered tothe test samples. The distribution ratio of colonies for each of the sixagar plates were used to calculate the mean particle size (MPS) of thechallenge aerosol. The filtration efficiencies were calculated as apercent difference between test sample runs and the control averageusing the following equation: ##EQU1## Where: C=Average of controlvalues. T=Count total for test material.

The Frazier porosity was measured in accordance with Federal Test Method5450 (Revised Mar. 18, 1992).

As can be see from Table II, the inner and outer wraps of the heavygrade sterilization system of the present invention provided an overallsystem with overall better grab tensile and peak energy values than theBaxter DualWrap® sterilization wrap. In addition, the heavy grade systemof the present invention had a lower dry spore penetration rate andtherefore a higher bacterial filtration efficiency than the Baxtermaterial.

                  TABLE II                                                        ______________________________________                                                             Kimguard                                                             DualWrap ® One Step ™ HG.sup.1                             Test Parameter                                                                              Inner  Outer     Inner                                                                              Outer                                     ______________________________________                                        Grab Tensile, lbs                                                             MD            14.4   27.5      37.1 45.4                                      CD            13.2   16.0      26.8 35.7                                      Peak Energy, in-lbs                                                           MD            1.1    11.8      37.2 46.8                                      CD            1.6    18.4      32.4 46.1                                      Dry Spore, ppt.sup.2                                                                        10.6   18.4      2.6  1.4                                       BFE.sup.3, %  73     56        78   73                                        Frazier Porosity                                                                            21.0   53.4      44.2 44.0                                      cu ft/sq ft/min.                                                              Basis weight, 1.55   2.02      1.89 2.49                                      osy                                                                           ______________________________________                                         .sup.1 Heavy Grade  contains 0.5 osy of meltblown fiber, the remaining        weight is spunbond fiber                                                      .sup.2 Particles per onethousand                                              .sup.3 Bacterial Filtration Efficiency                                   

Referring to Table III, the regular grade sterilization wrap system ofthe present invention when compared to the Baxter DualWrap®sterilization wrap provided comparable grab tensile values and betterpeak energy values. In addition, the regular grade sterilization wrapsystem had a lower dry spore penetration rate and thus a higherbacterial filtration efficiency due to the nature of the individualcomponents than did the DualWrap® sterilization wrap.

                  TABLE III                                                       ______________________________________                                                             Kimguard                                                             DualWrap ® One Step ™ RG.sup.1                             Test Parameter                                                                              Inner  Outer     Inner                                                                              Outer                                     ______________________________________                                        Grab Tensile, lbs                                                             MD            14.4   27.5      22.4 26.7                                      CD            13.2   16.0      14.2 20.2                                      Peak Energy, in-lbs                                                           MD            1.1    11.8      17.3 24.4                                      CD            1.6    18.4      13.8 23.2                                      Dry Spore, ppt.sup.2                                                                        10.6   18.4      0.8  1.2                                       BFE.sup.3, %  73     56        72   75                                        Frazier Porosity                                                                            21.0   53.4      47.8 73.0                                      cu ft/sq ft/min.                                                              Basis weight, 1.55   2.02      1.44 1.43                                      osy                                                                           ______________________________________                                         .sup.1 Regular Grade  the inner wrap contains 0.5 osy of meltblown fibers     and the outer wrap contains 0.3 osy of meltblown fibers with the              spunbonded fiber weight making up the difference in total weight.             .sup.2 Particles per onethousand                                              .sup.3 Bacterial Filtration Efficiency                                   

Actual in use product efficacy is the ultimate test of whether a productworks. To determine the functionality of the sterilization wrap systemof the present invention in protecting package contents fromcontamination, a study was performed on three sterilization wrap systemsall of which were used to wrap packages which were subsequentlysterilized using steam. For each of the three systems, 120 samples wereprepared and tested in an effort to determine the overall efficacy ofthe present invention relative to each. of the controls. As can be seenfrom Table IV, the first set of samples utilized the system of thepresent invention. The outer wrap 12 was a 1.4 ounces per square yardspunbonded/meltblown/spunbonded laminate including an inner meltblownlayer with a basis weight of 0.3 ounces per square yard and two outerspunbonded layers, each having a basis weight of 0.55 ounces per squareyard. The 1.4 ounce per square yard inner wrap 14 was also aspunbonded/meltblown/spunbonded laminate including a meltblown layerhaving a basis weight of 0.5 ounces per square yard and two outerspunbonded layers, each having a basis weight of 0.45 ounces per squareyard. The outer wrap 12 was ultrasonically bonded to the inner wrap 14in a manner similar to that shown in FIG. 1. Ultrasonic bondingtechniques and equipment are well known.

Control I was two unattached sheets of a current Kimberly-ClarkCorporation polypropylene sterilization wrap which historically hasshown less than 3% contamination when using sequential wrappingtechniques. Each of the unattached sterilization wrap sheets was madefrom a spunbonded/meltblown/spunbonded laminate having an approximateoverall basis weight of 1.4 ounces per square yard including a 0.4-0.5ounce per square yard meltblown layer and two approximately 0.45 ounceper square yard spunbonded layers.

Control II was two unattached sheets of muslin cloth with each sheetbeing made from two layers of 140 thread count muslin cloth sewntogether. Sterilized packages wrapped with two sheets of unattachedmuslin cloth have historically shown about 10%-26% contamination.

All 120 packages for each of the sample controls were prepared using adouble sequential wrapping method, that is, folding one sheet around thepackage followed by repeating the process by folding a second sheet ofwrap around the package. These packages were wrapped in this manner torepresent the most commonly used method of wrapping (double, sequentialwrapping). The 120 samples of the present invention was simultaneouslywrapped with two sheets of wrap which were ultrasonically bondedtogether. All the packages, including the controls, were sterilizedusing steam. Once sterilized, the packages were sent from theSterile-Processing Department of a hospital to the operating room andfrom the operating room back to storage to simulate a cancelledprocedure and then back to the operating room within a time period oftwo days. Package contents were then microbiologically cultured todetermine the percentage of contaminated packages. The results of thisstudy are given in Table IV.

                  TABLE IV                                                        ______________________________________                                        EVENTS RELATED STERILITY EFFICACY STUDY RESULTS                                             No. Packages                                                                           % Packages                                                           Contaminated                                                                           Contaminated                                           ______________________________________                                        Single Step Sterilization                                                                     1/120      0.83                                               Wrap System                                                                   (Ultrasonically                                                               fused polypropylene                                                           sterilization wrap)                                                           Control I -     0/120      0                                                  Kimberly-Clark                                                                polypropylene                                                                 sterilization wrap                                                            Control II -    12/120     10.0                                               140 Thread Count                                                              Cloth                                                                         ______________________________________                                    

As can be seen, the sterilization wrap system of the present inventiononly had one contaminated package out of 120 total packages, for apackage contamination percentage of 0.83%. Control I had nocontaminations and the Control II (cloth) system had 12 contaminationsper 120 packages for a package contamination percentage of 10%. At a 95%confidence level, the contamination level of the sterilization wrapsystem of the present invention and Control 1 were not statisticallydifferent. At the same 95% confidence level, both the sterilization wrapsystem of the present invention and Control I had significantly lowercontamination rates than Control II. As a result, it can be seen thatusing two attached sheets of sterile wrap in a simultaneous wrappingfunction protects packaged contents as well as double sequentialwrapping with unattached sheets.

The amount of time necessary to wrap and open a package is anotherimportant feature of the present invention and is particularly importantto hospitals in connection with the labor costs in preparing and openinghospital goods. To demonstrate packaging and opening time savingsincurred when using the present invention, an in-hospital time study wasconducted to compare the time it takes to wrap and open the system ofthe present invention discussed in Table IV and the Control I system andthe Control II system which were double sequentially wrapped and openedand also discussed in Table IV. As noted previously, the Control I andControl II systems were comprised of two sheets of sterilization wrapthat were not attached to one another. The simultaneous wrapping methodwith the present invention and the double sequential method with theControl I and II wraps were performed on a variety of items includingtowel packs, basins and instrument trays. The results are shown in TableV below.

                  TABLE V                                                         ______________________________________                                        SINGLE STEP STERILIZATION WRAP                                                                     TIME SAVINGS                                             SYSTEM VS.           WRAPPING  OPENING                                        ______________________________________                                        Control I            49%       48%                                            Control II           47%       42%                                            ______________________________________                                    

Based upon the time related study, the sterilization wrap system of thepresent invention provided a 49% savings of time in wrapping as comparedto the Control I system and a 47% time savings as compared to theControl II system. With respect to the opening of the sterilizedpackages, the sterilization system of the present invention provided a48% reduction in time for opening as compared to the Control I systemand a 42% savings of time as compared to opening with respect to theControl II system. Consequently, the bonding together of the outer wrap12 and inner wrap 14 of the sterilization wrap system of the presentinvention provides a real improvement in time savings with respect tothe handling/wrapping and unwrapping of sterilized packages in thehospital. As a practical matter, an item can be wrapped and unwrapped inalmost one half the time it takes with conventional double, sequentialwrapping. Consequently, the present invention can and does provide areal time and cost savings to the end user.

Having thus described the invention in detail, it should be apparentthat various modifications and changes can be made without departingfrom the spirit and scope of the present invention. For example, a widevariety of individual sterilization wraps have been described herein.Thus, a wide variety of combinations of inner and outer wraps arepossible including combinations of both disposable and reusable sterilewrap sheets. The inner and outer wraps may be made from the same ordifferent basis weight materials to engineer specific properties intoeach of the wraps. In addition, a wide variety of bonding techniqueswere also disclosed which may be used alone or in combination with eachother to impart varying bond patterns to the sterilization wrap systemof the present invention. Consequently, these and other modificationsare contemplated to be within the spirit and scope of the followingclaims.

What is claimed is:
 1. A method of sterilizing an articlecomprising:providing an article; wrapping the article with asterilization wrap system, wherein the sterilization wrap systemcomprises (a) an inner wrap sheet having a first peripheral edge and (b)an outer wrap sheet having a second peripheral edge; wherein at least aportion of the first peripheral edge is aligned with and not joined to aportion of the second peripheral edge; and wherein the inner wrap sheetand outer wrap sheet are joined to one another at one or more pointswithin an area surrounded by the peripheral edges; and exposing thewrapped article to sterilizing conditions for a sufficient time tosubstantially sterilize the article.
 2. The method of claim 1, whereinsaid sterilizing conditions are selected from steam sterilizingconditions or ethylene oxide sterilizing conditions.
 3. The method ofclaim 1, wherein one of the inner wrap sheet and the outer wrap sheethas a basis weight greater than the other sheet.
 4. The method of claim3, wherein the inner wrap sheet and the outer wrap sheet each have abasis weight of between about 0.5 and about 3.5 ounces per square yard.5. The method of claim 1, wherein each sheet has at least one edge, eachsheet is similarly sized, and at least one edge of one of the sheetsaligns with and is not joined to at least one edge of the other sheet.6. The method of claim 5, wherein said edges which align and are notjoined are substantially parallel edges.
 7. The method of claim 1,wherein one of the inner wrap sheet and the outer wrap sheet has a peakenergy greater than the other sheet.
 8. The method of claim 1, whereinthe inner wrap sheet is bonded to the outer bond sheet using bondingmeans selected from adhesive bonds, stitching bonds, heat bonds,ultrasonic bonds, or a plurality of bond points.
 9. The method of claim1, wherein both the inner wrap sheet and the outer wrap sheet each havea bacterial filtration efficiency greater than 70 percent.
 10. Themethod of claim 1, wherein the inner wrap sheet and the outer wrap sheetare made from a reusable material.
 11. The method of claim 1, whereinthe inner wrap sheet and the outer wrap sheet are made from a disposablematerial.
 12. The method of claim 1, wherein the outer wrap sheet has agreater grab tensile strength than the inner wrap sheet.
 13. The methodof claim 1, wherein the inner wrap sheet is capable of filtering agreater amount of bacteria than the outer wrap sheet.
 14. The method ofclaim 1, wherein each of the inner wrap sheet and the outer wrap sheetcomprise a meltblown layer; and wherein the meltblown layer of the innerwrap sheet has a heavier weight basis than the meltblown layer of theouter wrap sheet.
 15. The method of claim 1, wherein each of the innerwrap sheet and the outer wrap sheet comprise a meltblown layer; andwherein the meltblown layer of the outer wrap sheet has a heavier weightbasis than the meltblown layer of the inner wrap sheet.
 16. The methodof claim 1, wherein the sheets are joined together at a plurality ofbond sites which occupy less than about 50% of the surface area ofeither sheet.
 17. The method of claim 1, wherein said sheets are joinedtogether at a plurality of bond sites which occupy less than about 30%of the surface area of either sheet.
 18. The method of claim 1, whereinsaid sheets are joined together at a plurality of bond sites whichoccupy less than about 20% of the surface area of either sheet.
 19. Themethod of claim 1, wherein said sheets are joined together at aplurality of bond sites which occupy less than about 10% of the surfacearea of either sheet.
 20. The method of claim 1, wherein said sheets arejoined together at a plurality of bond sites which occupy less thanabout 5% of the surface area of either sheet.
 21. The method of claim 1,wherein at least one of said sheets comprises a meltblown layer.
 22. Themethod of claim 1, wherein at least one of said sheets comprises aspunbonded layer.
 23. The method of claim 1, wherein at least one ofsaid sheets comprises a meltblown/spunbonded layer.
 24. The method ofclaim 1, wherein at least one of said sheets comprises aspunbonded/meltblown/spunbonded layer.
 25. A method of sterilizing anarticle comprising:providing an article; wrapping the article with asterilization wrap which comprises an inner wrap sheet and an outer wrapsheet, wherein the sheets are joined together at a plurality of bondsites which occupy less than about 50% of the surface area of eithersheet, and wherein each of the inner wrap sheet and the outer wrap sheetcomprise a meltblown layer; wherein the meltblown layer of the innerwrap sheet has a basis weight which differs from a basis weight of themeltblown layer of the outer wrap sheet; and wherein each sheet has atleast one edge, and at least one edge of one of the sheets aligns withand is not joined to at least one edge of the other sheet; and exposingthe wrapped article to sterilizing conditions for a sufficient time tosubstantially sterilize the article.
 26. The method of claim 25, whereinsaid sterilizing conditions are selected from steam sterilizingconditions or ethylene oxide sterilizing conditions.
 27. The method ofclaim 25, wherein one of the inner wrap sheet and the outer wrap sheethas a basis weight greater than the other sheet.
 28. The method of claim27, wherein the inner wrap sheet and the outer wrap sheet each have abasis weight of between about 0.5 and about 3.5 ounces per square yard.29. The method of claim 25, wherein one of the inner wrap sheet and theouter wrap sheet has a peak energy greater than the other sheet.
 30. Themethod of claim 25, wherein the inner wrap sheet is bonded to the outerbond sheet using bonding means selected from adhesive bonds, stitchingbonds, heat bonds, ultrasonic bonds, or a plurality of bond points. 31.The method of claim 25, wherein both the inner wrap sheet and the outerwrap sheet each have a bacterial filtration efficiency greater than 70percent.
 32. The method of claim 25, wherein the inner wrap sheet andthe outer wrap sheet are made from a reusable material.
 33. The methodof claim 25, wherein the inner wrap sheet and the outer wrap sheet aremade from a disposable material.
 34. The method of claim 25, wherein theouter wrap sheet has a greater grab tensile strength than the inner wrapsheet.
 35. The method of claim 25, wherein the inner wrap sheet iscapable of filtering a greater amount of bacteria than the outer wrapsheet.
 36. The method of claim 25, wherein the meltblown layer of theinner wrap sheet has a heavier basis weight than the meltblown layer ofthe outer wrap sheet.
 37. The method of claim 25, wherein the meltblownlayer of the outer wrap sheet has a heavier basis weight than themeltblown layer of the inner wrap sheet.
 38. The method of claim 25,wherein the sheets are joined together at a plurality of bond siteswhich occupy less than about 30% of the surface area of either sheet.39. The method of claim 25, wherein said sheets are joined together at aplurality of bond sites which occupy less than about 20% of the surfacearea of either sheet.
 40. The method of claim 25, wherein said sheetsare joined together at a plurality of bond sites which occupy less thanabout 10% of the surface area of either sheet.
 41. The method of claim25, wherein said sheets are joined together at a plurality of bond siteswhich occupy less than about 5% of the surface area of either sheet. 42.The method of claim 25, wherein at least one of said sheets comprises aspunbonded layer.
 43. The method of claim 25, wherein at least one ofsaid sheets comprises a meltblown/spunbonded layer.
 44. The method ofclaim 25, wherein at least one of said sheets comprises aspunbonded/meltblown/spunbonded layer.
 45. The method of claim 25,wherein each sheet is similarly sized.
 46. The method of claim 25,wherein said edges which align and are not joined are substantiallyparallel edges.
 47. A sterilization wrap system comprising:an inner wrapsheet having a first peripheral edge and an outer wrap sheet having asecond peripheral edge;wherein at least a portion of the firstperipheral edge is aligned with and not joined to a portion of thesecond peripheral edge; and wherein the inner wrap sheet and outer wrapsheet are joined to one another at one or more points within an areasurrounded by the peripheral edges.
 48. The sterilization wrap system ofclaim 47, wherein means are provided to visually distinguish theseparate sheets.
 49. The sterilization wrap system of claim 48, whereinthe means to visually distinguish the separate sheets are selected froma word printed on one of the inner wrap sheet or the outer wrap sheet; alogo printed on one of the inner wrap sheet or the outer wrap sheet;different coloration of the separate sheets such that the inner wrapsheet is a different color than the outer wrap sheet; or differentshading of the separate sheets such that the inner wrap sheet is shadeddifferently than the outer wrap sheet.
 50. The sterilization wrap systemof claim 47, wherein the outer wrap sheet comprises a strength barrierweb laminate.
 51. The sterilization wrap system of claim 50, wherein thestrength barrier web laminate comprises a first strength layer made fromrandomly deposited fibers, a second strength layer made from randomlydeposited fibers, and an intermediate barrier layer made from randomlydeposited fibers, wherein the fibers in the intermediate barrier layerhave an average diameter less than the average diameter of the fibers ineither the first strength layer or the second strength layer.
 52. Thesterilization wrap system of claim 47, wherein the inner wrap sheetcomprises a barrier web laminate.
 53. The sterilization wrap system ofclaim 52, wherein the barrier web laminate comprises a third strengthlayer made from randomly deposited fibers, a fourth strength layer madefrom randomly deposited fibers, and a second intermediate barrier layermade from randomly deposited fibers, wherein the fibers in the secondintermediate barrier layer have an average diameter less than theaverage diameter of the fibers in either the first strength layer or thesecond strength layer.
 54. The sterilization wrap system of claim 47,wherein the sheets are joined together at a plurality of bond siteswhich occupy less than about 50% of the surface area of either sheet.55. The sterilization wrap system of claim 47, wherein said sheets arejoined together at a plurality of bond sites which occupy less thanabout 30% of the surface area of either sheet.
 56. The sterilizationwrap system of claim 47, wherein said sheets are joined together at aplurality of bond sites which occupy less than about 20% of the surfacearea of either sheet.
 57. The sterilization wrap system of claim 47,wherein said sheets are joined together at a plurality of bond siteswhich occupy less than about 10% of the surface area of either sheet.58. The sterilization wrap system of claim 47, wherein said sheets arejoined together at a plurality of bond sites which occupy less thanabout 5% of the surface area of either sheet.
 59. The sterilization wrapsystem of claim 47, wherein at least one of said sheets comprises ameltblown layer.
 60. The sterilization wrap system of claim 47, whereinat least one of said sheets comprises a spunbonded layer.
 61. Thesterilization wrap system of claim 47, wherein at least one of saidsheets comprises a meltblown/spunbonded layer.
 62. The sterilizationwrap system of claim 47, wherein at least one of said sheets comprises aspunbonded/meltblown/spunbonded layer.
 63. A sterilization wrap systemcomprising an inner wrap sheet and an outer wrap sheet, wherein thesheets are joined together at a plurality of bond sites which occupyless than about 50% of the surface area of either sheet, and whereineach of the inner wrap sheet and the outer wrap sheet comprise ameltblown layer, wherein the meltblown layer of the inner wrap sheet hasa basis weight which differs from a basis weight of the meltblown layerof the outer wrap sheet; and wherein at least one of said sheetscomprises a spunbonded/meltblown/spunbonded layer.
 64. The sterilizationwrap system of claim 63, wherein said sheets are joined together at aplurality of bond sites which occupy less than about 30% of the surfacearea of either sheet.
 65. The sterilization wrap system of claim 63,wherein said sheets are joined together at a plurality of bond siteswhich occupy less than about 20% of the surface area of either sheet.66. The sterilization wrap system of claim 63, wherein said sheets arejoined together at a plurality of bond sites which occupy less thanabout 10% of the surface area of either sheet.
 67. The sterilizationwrap system of claim 63, wherein said sheets are joined together at aplurality of bond sites which occupy less than about 5% of the surfacearea of either sheet.
 68. The sterilization wrap system of claim 63,wherein at least one of said sheets comprises a spunbonded layer. 69.The sterilization wrap system of claim 63, wherein at least one of saidsheets comprises a meltblown/spunbonded layer.